cc : Compute subtree has copy requests before property tree building

cc/layers/layer.h

Index: cc/layers/layer.h
diff --git a/cc/layers/layer.h b/cc/layers/layer.h
index 58dde9c4577aa05aca94dd2f73aab70af8e0f7d7..c215be42cf1b0c3d673dc965547ad7356a736145 100644
--- a/cc/layers/layer.h
+++ b/cc/layers/layer.h
@@ -97,6 +97,9 @@ class CC_EXPORT Layer : public base::RefCounted<Layer> {
   void RequestCopyOfOutput(std::unique_ptr<CopyOutputRequest> request);
   bool HasCopyRequest() const { return !inputs_.copy_requests.empty(); }
 
+  void SetSubtreeHasCopyRequest(bool subtree_has_copy_request);
+  bool SubtreeHasCopyRequest() const;
+
   void TakeCopyRequests(
       std::vector<std::unique_ptr<CopyOutputRequest>>* requests);
 
@@ -401,7 +404,7 @@ class CC_EXPORT Layer : public base::RefCounted<Layer> {
 
   void SetMayContainVideo(bool yes);
 
-  int num_copy_requests_in_target_subtree();
+  bool has_copy_requests_in_target_subtree();
 
   void SetElementId(ElementId id);
   ElementId element_id() const { return inputs_.element_id; }
@@ -627,6 +630,8 @@ class CC_EXPORT Layer : public base::RefCounted<Layer> {
   bool may_contain_video_ : 1;
   bool is_scroll_clip_layer_ : 1;
   bool needs_show_scrollbars_ : 1;
+  // This value is valid only when LayerTreeHost::has_copy_request() is true
+  bool subtree_has_copy_request_ : 1;
   SkColor safe_opaque_background_color_;
   std::unique_ptr<std::set<Layer*>> scroll_children_;